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Posts Tagged ‘testosterone’

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The 2D:4D ratio is considered a crude measure to indicate exposure to androgens (testosterone) in the womb. Testosterone exposure in utero has been correlated with various physical and behavioral traits.

The 2D:4D ratio is present before birth, ruling out any environmental causes. It is calculated by measuring the length of the right index finger from the crease where it joins the hand. A similar measure is taken of the right ring finger. Divide the length of the index finger of the right hand by the length of the ring finger. A longer index finger will result in a ratio higher than 1, while a longer ring finger will result in a ratio of less than 1. Ratios lower than 1 are correlated with testosterone exposure in the womb.

Some studies suggest that digit ratio correlates with health, behavior, and even sexuality in later life. Wikipedia has a list of traits correlated with digit digit ratio, including links out to detailed information about each one.

via Digit ratio – Wikipedia, the free encyclopedia.

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cientists have frequently questioned whether differences in competitive behavior could in part be explained by differing physiological responses to competition. In their new study, researchers from Harvard and Duke collected saliva from the apes using cotton wads dipped in Sweet Tarts candy, then measured hormone levels before and after pairs from each species were presented with a pile of food.

They found that males of both species who were intolerant and could not share with their partners showed hormonal changes in anticipation of competing for the food, but bonobos and chimpanzees were completely different in which hormones increased.

Male chimpanzees showed an increase in testosterone, which is thought to prepare animals for competition or aggressive interactions. By contrast, male bonobos showed an increase in cortisol, which is associated with stress and more passive social strategies in other animals.

“Chimpanzee males reacted to the competition as if it was a threat to their status, while bonobos reacted as if a potential competition is stressful by showing changes in their cortisol levels,” said Victoria Wobber, a Harvard graduate student and first author of the study.

Human males usually experience an increase in cortisol before many types of competition in a similar way as seen in the bonobos. However, if men have what is called a “high power motive,” or a strong desire to achieve high status, they experience an increase in testosterone before a competition.

“These results suggest that the steroid hormone shifts that are correlated with the competitive drive of men are shared through descent with other apes,” Wobber said.

via Some males react to competition like bonobos, others like chimpanzees.

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